automatic oil leak

[marvxyz1]

I have a 1980 gmc Sierra classic with automatic 6 cylinder, and have a oil leak in the area of where the speedometer goes into the transmission. the speedometer cable goes into a small box which is attached to the transmission. The oil seems to be leaking there. What is the box called?? I would like to look up the repair for it, and see if I can do it. I also have a leak coming from the plate, which covers the torque converter, what is this leak liklely coming from??? Thanks in advance for whatever information you can give me..